Lipids amp Membranes Diversity of Lipids Stored forms of energy derivatives of fatty acids oxidation is highly exergonic Structure h igh heat capacity mechanical protection absorb shocks ID: 931943
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Slide1
Biochemistry
Lecture
10
Lipids & Membranes
Slide2Slide3Diversity of Lipids
Stored forms of energy
derivatives of fatty acids
oxidation is highly exergonic
Structurehigh heat capacitymechanical protection (absorb shocks)esterified fatty acids at cell membraneswater repellantSignals and cofactorsfused carbon rings alter the location and function of fatty acids
3
Slide4Classification of lipids
Slide5Fatty Acids
Carboxylic acids with hydrocarbon chains containing from
4 to 36
carbons
Almost all natural fatty acids have an
even number of carbons Most natural fatty acids are
unbranched
Saturated:
no double bonds between carbons in the chain
Monounsaturated
:
one double bond between carbons in the alkyl chain
Polyunsaturated
:
more than one double bond in the alkyl chain
Slide6Fatty Acids
Carboxylic acids with hydrocarbon chains
4
36 carbons longbranched and unbranchedsaturated and unsaturatedpKa ~4.5
6
Slide7Slide8Trans v. Cis
D
ouble
Bonds in FAsMost naturally occurring unsaturated fatty acids have their double bonds in
cisTrans-unsaturated fats are correlated with high blood levels of cholesterol and cardiovascular diseaseTrans-unsaturated fats are also linked with inflammation8
Slide9Slide10Slide11Conformation of Fatty Acids
Slide12Slide13Triacylglycerols
Slide14Slide15Fats & Fuel Storage
Stored in adipose cells (fat cells) of animals and seeds of plants
Take up less storage space than carbohydrates
We have about 1 day worth of energy stored as carbohydrate
Our fat stores can help us survive for weeks
15
Slide16Membranes are Made from Lipids
Major membrane lipids:
Phospholipids
Glycerophospholipids
SphingolipidsSphingosineCeramideGlycolipidsCholesterol
Membrane lipids are all amphipathic: they have a nonpolar portion and also a polar portion16
Slide17Glycerophospholipids
17
Slide18Slide19Slide20Fluid Mosaic Model
Figure 21.2 The fluid mosaic model of membranes
.
Slide21Sterols
Slide22Steroids
Slide23What Can Pass T
hrough a Lipid
B
ilayer (Membrane)?
Nonpolar = GOIons, polar = STOP
23
Slide24How do molecules cross the cell membrane?
Simple diffusion
Facilitated diffusion (passive transport)
Active transport
Ion channels
24
Slide25Simple Diffusion vs. Transport
Simple diffusion requires passage through lipid bilayer.
A transporter reduces the energy required for polar molecules by providing a hydrophilic passage-way
25
Slide263 Classes of Transporters
26
Slide27Process requires no input energyPores and channels are
transmembrane
proteins with a central passage for ions and small molecules
Passive Transport (Facilitated Diffusion)
27
Slide28Active Transport
Process requires energy to move a solute up its electrochemical gradient
Primary Active Transport
: powered by a direct source of energy (e.g. ATP)
Secondary Active Transport
: couples the movement of one solute down a gradient with the movement of another solute up a gradient
28
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